#totop,#totop2{
    position: fixed;right: 0;bottom: 10px;
    width: 149px;height: 249px;overflow: hidden;
    cursor: pointer;display: none;
    background:url(../images/up.png) no-repeat 0px 0;
    z-index: 9999;
}
 
#totop2{
    background: url(../images/up.png) no-repeat -149px 0;
}